Vitreous glass sealed beam lamp units have been used for vehicle lighting since at least the 1930's in the United States. These lamps generally include a paraboloidal reflector having a highly mirrorized inner surface that usually has two central openings that receive connectors for a filament aligned within the reflector. The reflector is enclosed by a circular convex lens also constructed of glass that is located with respect to the reflector by various types of integral locating tabs and is joined to the reflector by heat fusion. The connector assemblies are also usually connected to the reflector by a heat fusion process, and the composition and pressure of gas within the reflector-lens envelope are carefully controlled through a filling tube formed integrally with the reflector, and this tube is fused after evacuation and/or, inert gas filling of the lamp envelope. Controlling the atmosphere within the envelope through the filling tube is extremely costly, and the filling tube must be carefully fused at the proper instant to achieve the desired atmosphere within the envelope.
Such a sealed beam lamp unit is shown and described in the D. K. Right U.S. Pat. No. 2,148,314 dated Feb. 21, 1939.
These sealed beam lamp units, which must be replaced after the filaments burn out, require complicated locking rings and adjustment assemblies, permanently carried by the associated vehicle to hold them in proper position. The locking rings frequently include adjusting brackets for varying the attitude of the lamp units to properly adjust the lamp's beam to effect the desired lamp alignment.
It has been suggested that the reflector of a rectangular sealed beam lamp unit be constructed of a plastic material with support flanges formed integrally with the plastic to eliminate the complicated mounting flanges and rings required in prior lamp units. Such a construction is shown in the Thomas T. Talon et al U.S. Pat. No. 4,188,655. This patent discloses a lamp with three integral flanges on a plastic reflector that cooperate with three adjusting assemblies mounted to the vehicle that permit adjustment of the lamp beam in two orthogonal planes. While such an arrangement is suitable for many passenger automobile applications it is nevertheless quite costly because of the three separate fastening and adjusting mechanisms required.
Self-housed lamp units have also been provided in the past that include cup-shaped housings that enclose a replaceable sealed beam lamp unit. These self-housed lamp units are useful for mounting on a vehicle panel with the lamp projecting from the panel as opposed to mounting arrangements where the lamp unit is inserted into an aperture in a vehicle panel (flush mounting). The self-housed lamp units usually require a mounting bracket, usually a pivot mount bracket, to attach the lamp unit to the vehicle panel and also to permit adjustment of the attitude of the lamp as desired by the operator of the vehicle. In the past, one or more mounting rings bezels and sometimes threaded fasteners through the rings and bezels have been required to mount the sealed beam lamp unit within the housing not only adding to the original cost of manufacture of the lamp unit but also making lamp replacement difficult.
It is a primary object of the present invention to ameliorate the above noted problem in sealed beam lamp units and particularly in self-housed lamp units.